Coolant compressor

ABSTRACT

The invention relates to a coolant compressor having a compressor housing (6), an electric drive unit comprising a rotor (4) and a stator (3), a crankshaft (1) rotationally fixedly connected to the rotor (4) and having a longitudinal axis (2); and a piston-cylinder unit (5) that can be driven by the crankshaft (1). In order to permit an increased feed rate of lubricant from a lubricant sump, according to the invention, on an end of the crankshaft (1) that is opposite to the piston-cylinder unit (5) there is arranged a sleeve-like lubricant receptacle (8) for the centrifugal delivery of lubricant out of the lubricant sump in the direction of the piston-cylinder unit (5), wherein the sleeve-like lubricant receptacle (8) is fixed to the crankshaft (1) via a fixing section (9), wherein the fixing section (9) of the sleeve-like lubricant receptacle (8) is at least partly arranged between crankshaft (1) and rotor (4) in the radial direction in relation to the longitudinal axis (2) of the crankshaft (1).

FIELD OF THE INVENTION

The invention relates to a refrigerant compressor having a compressor housing, preferably hermetically sealable, an electric drive unit comprising a rotor and a stator, a crankshaft that is rotationally fixedly connected to the rotor and has a longitudinal axis, and piston-cylinder-unit drivable by the crankshaft.

PRIOR ART

Refrigerant compressors, especially hermetically encapsulated refrigerant compressors, have long been known and are primarily used in cooling appliances such as refrigerators or refrigerating shelves. The refrigerant process as such has likewise been known for a long time. Refrigerant is heated in an evaporator by absorbing energy from the space to be cooled and finally superheated and is pumped to a higher pressure level by means of the refrigerant compressor, via a piston-cylinder-unit using a piston moving translationally in a cylinder housing, where the refrigerant outputs heat via a condenser and is conveyed back into the evaporator via a throttle valve, in which a pressure reduction and a cooling down of the refrigerant take place. The movement of the piston is implemented via a crank assembly driven by an electric drive unit and comprising a crankshaft.

The electric drive unit comprises a stator, which is generally formed from a laminated stack and wire windings, and a rotor generally comprising a plurality of permanent magnets, wherein the rotor is rotationally fixedly connected to the crank assembly, more particularly the crankshaft, i.e. form-fitted, frictionally fitted or integrally bonded. The drive unit is typically designed either as an asynchronous motor, wherein the stator consists of a laminated stack and/or copper or aluminum wire windings and the rotor consists of a laminated stack and aluminum connecting pieces together with aluminum shading circuit rings, or as a synchronous motor, wherein the stator comprises a laminated stack and/or copper or aluminum wire windings and the rotor comprises a plurality of permanent magnets.

In order to lubricate the piston-cylinder-unit and the crank assembly, more particularly the crank shaft, during operation, a lubricant-conveying system is provided, by means of which lubricant building up during operation in a lubricant sump in a bottom region of the compressor housing is conveyed in the direction of the piston-cylinder-unit during operation of the refrigerant compressor.

The lubricant-conveying system is generally formed at least in part by the crankshaft itself, wherein the crankshaft has at least one axial bore and/or an eccentric bore at the end opposite from the piston-cylinder-unit, preferably at an end face of the crankshaft, through which bore lubricant is conveyed in the direction of the piston-cylinder-unit by the centrifugal force during rotation of the crankshaft. In addition, or alternatively, the crankshaft often has a helical groove formed on the circumferential surface in a central section, which groove conveys the lubricant on the circumferential surface upwards and is connected to the axial bore and/or the eccentric bore.

A disadvantage of the prior art is manifested in the fact that the overall conveying power of the lubricant-conveying system is reduced due to the conveyance height of the lubricant that must be overcome, particularly when taking the lubricant out of the lubricant sump. This reduction of conveying power with increasing conveyance height results from the diminishing quantity of lubricant that can be delivered by conveyance based on the centrifugal force.

AIM OF THE INVENTION

The problem addressed by the present invention is therefore that of overcoming the disadvantages of the prior art and proposing a refrigerant compressor that enables an increased conveying power of lubricant from a lubricant sump with a comparatively smaller or reduced overall height of the compressor.

PRESENTATION OF THE INVENTION

In order to introduce lubricant into a bore running parallel to a longitudinal axis of the crankshaft or at an angle to the longitudinal axis, preferably an eccentric bore arranged eccentrically to the longitudinal axis of the crankshaft, without the end of the crankshaft opposite the piston-cylinder-unit protruding far from the rotor and without the end of the crankshaft opposite from the piston cylinder unit being immersed into the lubricant sump, and a sleeve-shaped lubricant receptacle is arranged at the end of the crankshaft. The lubricant receptacle has a fastening portion via which the lubricant receptacle can be fastened to the crankshaft, preferably rotationally fixedly, i.e. form-fitted, frictionally fitted or integrally bonded. Due to the fixation to the crankshaft, the lubricant receptacle rotates together with the crankshaft in the operating state.

The sleeve-shaped lubricant receptacle dips into the oil sump in the operating state, wherein lubricant can enter the lubricant receptacle, for example via a lubricant inlet opening. The lubricant receptacle is typically produced from a metallic material or from a plastic. Due to the sleeve-shaped formation of the lubricant receptacle as a hollow body in which lubricant can be received, lubricant present in the lubricant receptacle is pressed by centrifugal force against the inner wall of the lubricant receptacle, whereby the pressure increases and the lubricant is conveyed in the direction of the end of the crankshaft. In the process, a lubricant parabola or a paraboloid-shaped lubricant column typically forms inside the lubricant receptacle.

In order to reduce the conveyance height to be overcome by the lubricant and thus increase the conveying power despite the fastening of the lubricant receptacle to the crankshaft, it is provided that the fastening portion of the lubricant receptacle is arranged at least in certain portions between the motor and the crankshaft. In other words, the fastening portion, the crankshaft and the rotor overlap at least in certain portions. Due to the fastening of the lubricant receptacle in the region of the rotor, the distance between the rotor and the oil sump can be reduced, which causes an improved oil conveyance and an increased conveying power. A sufficient lubrication of the piston-cylinder-unit can be guaranteed even at lower rotational speeds thanks to the higher conveying power, and therefore the refrigerant compressor can be operated in the most energy-optimized manner possible. In addition, the portion of the crankshaft protruding from the rotor can be reduced, which results in both material savings and a reduction of the conveyance height and simultaneously enables a reduction of the overall installation height of the refrigerant compressor.

The problem posed above is thus solved in the refrigerant compressor according to the invention in that a sleeve-shaped lubricant receptacle for centrifugal conveyance of lubricant in the direction of the piston-cylinder-unit from a lubricant sump formed in the bottom area of the compressor housing is arranged at an end of the crankshaft opposite from the piston-cylinder-unit, the sleeve-shaped lubricant receptacle having a fastening portion by means of which fastening portion the lubricant receptacle can be fastened to the crankshaft, preferably rotationally fixedly, the fastening portion of the sleeve-shaped lubricant receptacle being arranged, in the radial direction relative to the longitudinal axis of the crankshaft, between the crankshaft and the rotor, at least in certain portions.

One embodiment variant of the invention provides that an inner surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts a circumferential surface of the crankshaft and that an outer surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts an inner surface of the rotor. The radius of the lubricant receptacle is maximized by virtue of the fact that the fastening portion contacts both the crankshaft and a portion of the rotor. In addition, the number of assembly steps during the assembly of the crankshaft, rotor and lubricant receptacle is reduced. The inner surface of the rotor can be formed, for example, by a through. opening, preferably arranged centrally.

A further embodiment variant of the refrigerant compressor according to the invention provides that the fastening portion of the sleeve-shaped lubricant receptacle is fixed between the rotor and the crankshaft in a rotationally fixed manner. The rotationally fixed fastening ensures that the lubricant receptacle co-rotates along with the crankshaft. Due to the fixation between rotor and crankshaft, a slippage of the lubricant receptacle can be prevented, with no additional fixing means being necessary. For example, the fastening portion can be clamped between the rotor and the crankshaft or plastically deformed by the mounting of the rotor. It is also conceivable that the fastening portion can be shrink-fitted or pressed onto the crankshaft and that the rotor can be pressed or shrink-fit onto the fastening portion at least in certain portions.

In order to maximize the conveying power and minimize the increase of the conveyance height caused by the fastening of the fastening portion to the crankshaft, another embodiment variant provides that an overlap of rotor and fastening portion in the axial direction is greater than 50% relative to the longitudinal axis, preferably greater than 75% and more particularly between 75% and 100% of the axial extent of the fastening portion relative to the longitudinal axis. Overlaps of 60%, 70%, 80%, 85%, 90% or 95% are conceivable for example.

A preferred embodiment variant of the invention provides that the sleeve-shaped lubricant receptacle has a rotationally symmetrical shape relative to the longitudinal axis, the diameter of the fastening portion being greater than or at least equal to the diameter of a receiving portion of the lubricant receptacle. The rotationally symmetrical shape reduces the flow resistance of the receiving portion, which is arranged in the lubricant sump in operation, during rotation of the crankshaft. The selection of the diameter of the fastening portion facilitates the connection of the fastening portion to the crankshaft, because the crankshaft is also rotationally symmetrically shaped, at least in the region of an end portion. If the diameter of the fastening portion is greater than that of the receiving portion, the diameter of the receiving portion can be adapted to the diameter of the crankshaft in order to achieve an improved oil conveyance.

Another embodiment variant of the refrigerant compressor according to the invention provides that the fastening portion of the sleeve-shaped lubricant receptacle extends parallel to the longitudinal axis and that the sleeve-shaped lubricant receptacle comprises a collar portion adjoining the fastening portion and extending radially outward relative to the longitudinal axis, the collar portion preferably bearing against the rotor. While the fastening portion extends parallel to the longitudinal axis, in other words forms a circular cylindrical sleeve in order to enable easy assembly, the collar portion prevents the lubricant receptacle from shifting in the axial direction, i.e. parallel to the longitudinal axis, because the collar portion either bears against a bearing sleeve of the crankshaft or against the rotor. At the same time, the collar portion can serve as a stop for the installation of the rotor. In any case, it is advantageous for the positioning of rotor, crankshaft and lubricant receptacle during assembly if the collar portion bears against the rotor, for example on an upper side of the rotor facing the piston cylinder unit or against a surface of the rotor facing the piston cylinder unit.

In order to improve the fastening of the rotor to the crankshaft, another preferred embodiment variant of the invention provides that the fastening portion of the sleeve-shaped lubricant receptacle has at least one slot-like cutback, preferably extending parallel to the longitudinal axis over the entire extent of the fastening portion, the rotor comprising at least one ridge corresponding to the cutback. The at least one ridge engages with the at least one cutback so that the rotor directly contacts the crankshaft in the region of the recess. Thus the rotor is fastened directly to the crankshaft in some portions, while in the regions having the fastening portion, the fastening portion functions as an intermediate layer between the rotor and the crankshaft. For example, the cutback can be configured as a slot-like recess or a plurality of slot-like recesses that run in the axial direction, i.e. parallel to the longitudinal axis, from the upper end of the lubricant receptacle into the fastening portion. A plurality of cutbacks are preferably arranged distributed uniformly across the periphery of the fastening portion.

A preferred embodiment variant of the invention provides that the electric drive unit is configured as an external-rotor motor and the rotor has at least one carrier element extending outward radially to the longitudinal axis, at least in certain portions, the carrier element being rotationally fixedly connected to the crankshaft. Due to the configuration of the drive unit as an external-rotor motor, in which the stator is radially inside relative to the longitudinal axis and the rotor is arranged relatively outward., the carrier element serves as a connection between the electromagnetic components of the rotor, for example permanent magnets distributed across the periphery and connected by a shading circuit ring, and the crankshaft, which can be driven by the electromagnetic interaction between the rotor and the stator. The external-rotor motor design enables a particularly low installation height of the refrigerant compressor and is characterized by very quiet running in different speed ranges. By combining an external-rotor motor with a lubricant receptacle according to the invention, a particularly high oil conveying rate can be achieved, or a sufficient oil conveying rate can be achieved at particularly low rotational speeds. The through-opening can be formed. for example, by bulging in a bending or deep drawing process, of a sheet metal part forming the carrier element.

Another particularly preferred embodiment variant provides that the carrier element has a central through-opening for connecting the crankshaft, wherein an outer surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts a wall surface of the through-opening. Due to this arrangement of carrier element, fastening portion and crankshaft, a particularly space-saving fixation of the carrier element and the lubricant receptacle on the crankshaft is possible, because the through-opening is used for fastening the carrier element to the crankshaft, and as an intermediate layer between crankshaft and carrier element, the fastening portion occupies no additional construction space, particularly in the axial direction. Thereby the conveyance height of the lubricant from a surface of the lubricant sump to a radial bore for lubricating a main bearing of the crankshaft and/or to a radial bore for connection to a helical groove is minimized. At the same time, a protrusion of the crankshaft from the through-opening in the direction of the bottom region of the compressor housing is not necessary or can be drastically reduced, because the fastening portion of the lubricant receptacle is arranged in the through-opening between the rotor and the crankshaft and need not be mounted on the protrusion of the crankshaft.

In order to increase the surface pressure between the wall surface of the through-opening and the outer surface of the fastening portion of the sleeve-shaped lubricant receptacle, and the surface pressure between the inner surface of the fastening portion and the circumferential surface of the crankshaft, and thus improve the holding force of the fastening portion on the crankshaft and/or that of the carrier element on the crankshaft, another particularly preferred embodiment variant of the invention provides that the through-opening is formed by a sleeve-shaped prolongation of the carrier element and that an annular support element is pressed onto or shrink-fitted onto the sleeve-shaped prolongation. The sleeve-shaped prolongation preferably extends onto the side of the carrier element facing away from the piston-cylinder-unit, the sleeve-shaped prolongation being constructed integrally with the carrier element, by means of a forming process, for example. The shrink-fitted or pressed-on annular support element exerts a force directed radially inward in the direction of the longitudinal axis onto an outer circumferential surface of the prolongation, so that the clamping force or the resulting surface pressure is increased. This secures both the rotationally fixed, i.e. friction-fitting or force-fitting connection of the carrier element to the crankshaft and the rotationally fixed, i.e. friction-fitting or force-fitting connection of the lubricant receptacle to the crankshaft. The support element need not extend over the entire extent of the prolongation in the direction of the longitudinal axis; partially overlapping is sufficient, an overlapping of at least 20%, preferably more than 50%, more particularly more than 75%, being advantageous.

Another, particularly preferred embodiment variant of the invention provides that the electric drive unit is designed as an internal-rotor motor, and the rotor has a central through-opening for connection to the crankshaft, wherein an outer surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts a wall surface of the through-opening. In an internal-rotor motor, which generally can be produced very economically, the rotor is arranged radially internally in relation to the longitudinal axis, while the stator is arranged radially externally. The rotor, constructed as a rotor laminated stack for example, has a central through-opening that is used in some portions for fastening to the crankshaft. A cutback adjoining the through-opening can be provided in order to receive a portion of a bearing bushing protruding into the rotor to support the crankshaft, wherein the bearing bushing can be formed from a support housing of the piston-cylinder-unit. Since the rotor is generally connected to the crankshaft at the end opposite from the piston-cylinder-unit, the fastening portion of the lubricant receptacle simultaneously has a compensating effect on the helical line effect occurring with short clamping lengths of the laminations in the rotor laminated stack. This reduces an air gap fault between rotor and stator induced by the helical line effect and results in a higher efficiency of the refrigerant compressor. In addition, a protrusion of the crankshaft past the lowest lamination of the rotor laminated stack is not necessary or can be drastically reduced, because the fastening portion of the lubricant receptacle is arranged in the through opening between the rotor and the crankshaft, and need not be secured at the protrusion of the crankshaft.

In both particularly preferred embodiment variants, i.e. in the external-rotor motor embodiment and the internal-rotor motor embodiment, it is advantageous if the lubricant receptacle, more particularly the fastening portion thereof, extends through the entire through-opening.

In order to improve the conveyance of the lubricant within the lubricant receptacle, particularly in the receiving region, another preferred embodiment variant of the invention provides that a lubricant driver is arranged in the interior of the sleeve-shaped lubricant receptacle, the lubricant driver and the lubricant receptacle preferably being formed integrally. The lubricant driver is arranged centrally and can comprise one or more helical or planar surfaces for pushing the lubricant outward in the direction of the inner wall of the lubricant receptacle or in the axial direction upwards in the direction of the bore of the crankshaft. As a rule, the lubricant receptacle and the lubricant driver are formed in two parts, with the lubricant driver being mounted in the interior of the lubricant receptacle. It can also be advantageously provided that the lubricant driver and the lubricant receptacle are integrally formed; for example, if the fastening portion has cutbacks, the material of the cutbacks can be bent inwards and function as a lubricant driver. An integral embodiment variant produced by means of a 3D printing process (rapid prototyping) is also conceivable.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be explained in detail with reference to embodiments. The drawings are for the sake of example and are intended to present the inventive concept, but not to restrict it, much less reproduce it exhaustively.

Therein:

FIG. 1 shows a sectional representation of a first embodiment variant of a refrigerant compressor according to the invention;

FIG. 2 shows an enlarged detail representation of a bottom region of the refrigerant compressor according to FIG. 1;

FIG. 3 shows an additional enlarged detail representation according to FIG. 1;

FIG. 4 shows a sectional representation of a second embodiment variant of a refrigerant compressor according to the invention;

FIG. 5 shows a sectional representation of a third embodiment variant of a refrigerant compressor according to the invention;

FIG. 6 shows an enlarged detail representation of the bottom region of the refrigerant compressor according to FIG. 5.

MODES FOR EMBODYING THE INVENTION

FIGS. 1 to 3 show a first embodiment variant of a refrigerant compressor according to the invention, having a drive unit configured as an external rotor motor, which is arranged in the interior of a compressor housing 6 that can be hermetically encapsulated. The drive unit comprises a stator 3 and a rotor 4. A crankshaft 1 having a longitudinal axis 2 is arranged centrally relative to the stator 3 and the rotor 4, which crankshaft 1 is connected rotationally fixedly, e.g. form-fittingly, friction-fittingly or integrally, to the rotor 4 in order to drive the piston-cylinder-unit 5 of the refrigerant compressor that cyclically compresses a refrigerant. The crankshaft 1 is mounted in a bearing bushing 17 of a carrier housing 18 carrying the piston cylinder unit 5. The stator 3, which is arranged internally in the radial direction relative to the longitudinal axis 2, subsequently referred to as the radial direction, is fastened to the outer side of the bearing bushing 17.

The crankshaft 1 is part of a crank assembly, which comprises a crank pin 26 offset eccentrically with respect to the longitudinal axis 2 and connected directly to the crankshaft 1. The piston-cylinder-unit 5 comprises a piston 25, which is guided movable linearly in a cylinder housing 24, a connecting rod 23 connecting the crank pin 26 to the piston 25, a cylinder head arrangement 27 comprising valves, and a suction muffler 28 connected to the cylinder head arrangement 27.

In the present embodiment, the carrier housing 18 and the cylinder housing 24 are integrally formed, more precisely as a cast part. The carrier housing 18 has multiple prolongations, via which the carrier housing 18 is supported on spring elements 29 in the compressor housing 6 that are arranged in a bottom region 7 of the compressor housing 6. In alternative embodiments, carrier housing 18 and cylinder housing 24 can be formed in two parts and connected to one another via connecting means.

The rotor 4 comprises, as illustrated in FIG. 2, a plurality of permanent magnets 14, which are arranged outside the stator 3 in the radial direction and are connected to one another in the circumferential direction via a shading circuit ring 15. In order to connect the permanent magnets 14 to the crankshaft 1 by means of a force fit or friction fit, the rotor 4 has a carrier element 12 extending radially outward from the crankshaft 1 and reaching underneath the stator 3. The carrier element 12 is formed substantially in a plate shape and has an elevated edge portion curved in the direction of the piston cylinder unit 5, at which edge portion the permanent magnets 14 and the shading circuit ring 15 are mounted. For connection to the crankshaft 1, the carrier element 12 has a centrally arranged through-opening 13 for positioning the rotor 4 coaxially with respect to the longitudinal axis 2. The carrier element 12 in the present embodiments has a sleeve-shaped prolongation 12 a with a circular cylindrical clear cross section, which is arranged centrally, and extends onto the side of the carrier element 12 facing away from the piston cylinder unit 5. The through-opening 13 is formed by the prolongation 12 a. Carrier element 12 and prolongation 12 a in the present example are integrally formed, the prolongation 12 a and the edge portion being formed from the carrier element 12 by means of a deep drawing process, for example.

In order to lubricate the bearing points of the crankshaft 1 in the bearing bushing 17, and the piston-cylinder-unit 5 in an operating state of the refrigerant compressor and to supply them with lubricant from a lubricant sump formed in the operating state in the bottom region 7 of the compressor housing 6, the crankshaft 1 has, at the end opposite from the piston-cylinder-unit 5, i.e. the lower end, an eccentric bore 19 arranged eccentrically relative to the longitudinal axis 2 in the radial direction and running at an angle relative to the longitudinal axis 2. Lubricant that reaches the eccentric bore 19 is pressed against the wall of the eccentric bore 19 by the centrifugal force during rotation of the crankshaft 1 and is conveyed in the direction of the piston cylinder unit 5 by the elevated pressure. In the present embodiment, the eccentric bore 19 is configured as a blind hole and is connected at the end facing the piston-cylinder-unit 5 by a first radial bore 20 to a helical groove 22 formed on the circumferential surface of the crankshaft 1 in order to convey the lubricant. A second radial bore 21, which is arranged closer to the lower end of the crankshaft 1 as viewed in the direction of the longitudinal axis 2, is used for venting the lubricant system. The conveyance speed is increased by the venting and simultaneously a negatively acting pulsation is prevented.

In alternative embodiment variants, the eccentric bore 19 can also be arranged running parallel to the longitudinal axis 2 or, instead of the eccentric bore, an axial bore running coaxially relative to the longitudinal axis 2 can be provided.

In order to bring lubricant out of the lubricant sump into the eccentric bore 19 without the necessity for a free end of the crankshaft 1 to dip into the lubricant sump, a sleeve-shaped lubricant receptacle 8 is provided, which is rotationally fixed to the crankshaft 1 at the end of the crankshaft 1 remote from the piston-cylinder-unit 5, and thus rotates along with the crankshaft 1. Lubricant enters into a receiving portion 10 of the lubricant receptacle 8 via a lubricant entry opening. Because the lubricant receptacle 8 has a rotationally symmetrical shape relative to the longitudinal axis 2 and is arranged coaxially with the longitudinal axis 2, a lubricant parabola or a paraboloid shaped lubricant column is formed in the lubricant receptacle 8 by the rotation of the lubricant receptacle 8, and passes at the lower end of the crankshaft 1 into the eccentric bore 19 and is conveyed on from there in the direction of the first radial bore 20.

As the distance between the surface level of the lubricant sump and the first radial bore 20, also referred to as the conveyance height, increases, the conveying power of the lubricant-conveying system decreases. It is therefore one aspect of the invention that a fastening portion 9 of the sleeve-shaped lubricant receptacle 8 is arranged between the rotor 4 and the crankshaft 1. Due to the overlapping of fastening portion 9, rotor 4 and crankshaft 1, a particularly space-saving connection of the lubricant receptacle 8 to the crankshaft 1 can be achieved, whereby the conveyance height can be lowered and thus the conveying power, i.e. the lubricant feed rate per minute, can be increased. The increase of the conveying power can be explained by the fact that, due to the lower conveyance height, the wall thickness of the lubricant paraboloid in the region of the second radial bore 20 is greater and thus more lubricant reaches the helical groove 22. Due to the higher conveying power, a sufficient lubrication of the piston-cylinder-unit 5 can be guaranteed even at lower rotational speeds, so that the refrigerant compressor can be operated as energy-optimally as possible.

The greater the overlap between fastening portion 9, rotor 4 and crankshaft 1, the lower the conveyance height of the lubricant. In addition to this, it is not necessary for the crankshaft 1 to protrude from the rotor 4 in order to receive the fastening portion 9 of the lubricant receptacle 8, because the rotor 4 is fastened to the crankshaft 1 and the lubricant receptacle 8 is fastened by means of the fastening portion 9 in the same region of the crankshaft 1, namely at the lower end thereof. In the present embodiment, an inner surface of the fastening portion 9 contacts an outer circumferential surface of the crankshaft 1 and an outer surface of the fastening portion 9 contacts an inner surface of the rotor 4, more precisely a wall surface of the through-opening 13. As can be easily recognized in the drawing, the fastening portion 9 has a circular cylindrical clear cross section, in which the lower end of the crankshaft 1 is received, while the carrier element 12 of the rotor 4 bears against the outer surface of the fastening portion 9. The rotor 4 is thus fastened to the crankshaft 1 by interposition of the fastening portion 9 of the sleeve-shaped lubricant receptacle 8, at least in certain portions. While through-opening 13, fastening portion 9 and the lower end of crankshaft 1 overlap completely in the present embodiment, other embodiments can also provide a partial overlapping of through-opening 13 and fastening portion 9, e.g. an overlap of 50%, 75%, 80%, 85%, 90% or 95% relative to the axial extent of the fastening portion 9.

As can be recognized in detail in FIG. 3, a collar portion 11 adjoins the fastening portion 9 on the side of the fastening portion 9 opposite from the receiving portion 10, which collar portion 11 protrudes at an angle from the fastening portion 9 and extends in the radial direction. In the present embodiment, the collar portion 11 protrudes at a right angle from the fastening portion 9 and bears against an upper side of the carrier element 12 facing the piston-cylinder-unit 5. The collar portion 11 can be used as a stop during assembly, for example. At the same time, the axial play of the crankshaft 1 can be adjusted by the attachment of the lubricant receptacle 8 during the assembly of the crankshaft 1, because the contour of the bearing bushing 17 and the collar portion 11 overlap in the direction of the longitudinal axis 2, so that the rotor 4 need not be installed until a subsequent assembly step, without the risk of an axial slippage of the crankshaft 1 in the bearing bushing 17. The inclination of the axis of the eccentric bore 19 by approximately 3° to 7° relative to the longitudinal axis 2, and the arrangement of the first radial bore 20 and the second radial bore 21, wherein the openings of the two radial bores 20, 21 are arranged opposite from one another, can also be clearly recognized in FIG. 3.

FIG. 4 shows a second embodiment variant of the invention, which differs only slightly from the first embodiment variant, and therefore only the differences will be discussed below. To improve the connection of the carrier element 12 to the crankshaft 1 and increase the surface pressure between carrier element 12 and fastening portion 9, and between fastening portion 9 and crankshaft 1, an annular support element 30 is pressed onto or shrink-fitted onto the prolongation 12 a. In other words, the support element 30 contacts an outer circumferential surface of the prolongation 12 a and exerts a force directed radially inward in the direction of the longitudinal axis 2 onto the fastening portion 9. This force increases the surface pressure and thus the quality of the force-fitting or friction-fitting connection between the wall surface of the through-opening 13 and the outer surface of the fastening portion 9 and between the inner surface of the fastening portion 9 and the circumferential surface of the crankshaft 1. The support element 30 contacts a lower side of the carrier element 12 and overlaps approximately 80% of the prolongation 12 a.

FIGS. 5 and 6 show a third embodiment of a refrigerant compressor according to the invention, in which the drive unit is configured as an internal-rotor motor. The rotor 4 is thus arranged inside the stator 3 relative to the longitudinal axis 2. A rotor stack, comprising lamina-like rotor sheets for example, is fastened directly to the crankshaft 1. In this case, the rotor 4 or the rotor laminated stack of the rotor 4 has a central through-opening 13, which is used firstly for fastening to the crankshaft 1 and secondly has a cutback for receiving the bearing bushing 17, because the bearing bushing 17 protrudes axially into the rotor 4.

The structure of the piston-cylinder-unit 5 corresponds substantially to the structure described in FIG. 1. Because the crankshaft 1 has not been cut away, it is easy to recognize the contour of the helical groove 22, which is formed analogously to the that in the previous embodiments.

In this embodiment variant as well, the conveying power of the lubricant-conveying system can be improved because the fastening portion 9 of the sleeve-shaped lubricant receptacle 8 is arranged between rotor 4 and crankshaft 1. The inner surface of the fastening portion 9 contacts the outer circumferential surface of the lower end of crankshaft 1, while the outer surface of the fastening portion 9 contacts the inner surface of the rotor 4, more precisely a wall surface of the through-opening 13. In the present embodiment, the dimension of the fastening portion 9 in the direction of the longitudinal axis 2 is selected such that the fastening portion 9 crosses through the entire through-opening 13, and the collar portion 11 bears against an upper surface of the rotor 4 that faces the piston-cylinder-unit 5. Thus the lubricant receptacle 8 can be pushed from above into the rotor 4 during assembly, wherein the collar portion 11 serves as a stop. Alternative embodiment variants can provide that the lubricant receptacle 8 does not have a collar portion 11 and is inserted only in certain portions into the through-opening 13.

Both embodiment variants can provide that the fastening portion 9 has one or more, for example two, three or four, slot-like cutbacks, which correspond to ridges of the rotor, or to ridges formed in the through-opening 13. When the ridges engage with the cutbacks, a direct contact between rotor 4 and crankshaft 1 in these portions is possible, without interposition of the fastening portion 9 of the lubricant receptacle 8. This can improve the rotationally fixed fastening of the rotor 4 to the crankshaft 1. The fastening portion 9 of the lubricant receptacle 8 and the through-opening 13 of the rotor 4 are normally pressed onto or shrink-fitted onto the crankshaft 1.

In addition, a lubricant driver 16, which supports the formation of the lubricant paraboloid and increases the conveying power of the conveying device, can be arranged in the lubricant receptacle 9 [sic; 8]. Thus a lubricant driver 16 is arranged in the lubricant receptacle 8 in each of the above-described embodiments, and has at least one or more helical surfaces facing outward in the direction of the inner wall of the lubricant receptacle 8 or facing upward in the direction of the eccentric bore 19 of the crankshaft 1 in order to force the lubricant upward in the axial direction. It is also conceivable that one or more surfaces of the lubricant driver 16 are planar in shape.

LIST OF REFERENCE NUMBERS

1 Crankshaft

2 Longitudinal axis of crankshaft 1

3 Stator

4 Rotor

5 Piston-cylinder-unit

6 Compressor housing

7 Bottom region of compressor housing 6

8 Sleeve-shaped lubricant receptacle

9 Fastening portion of lubricant receptacle 8

10 Receiving portion of lubricant receptacle 8

11 Collar portion

12 Carrier element of rotor 4

12 a Sleeve-shaped prolongation of carrier element 12

13 Through-opening

14 Permanent magnet

15 Shading ring

16 Lubricant driver

17 Bearing bushing

18 Carrier housing

19 Eccentric bore

20 First radial bore

21 Second radial bore

22 Helical groove

23 Connecting rod

24 Cylinder housing

25 Piston

26 Crank pin

27 Cylinder head arrangement

28 Suction muffler

29 Spring element

30 Annular support element 

What is claimed is:
 1. A refrigerant compressor comprising a housing; an electric drive unit comprising a rotor and a stator; a crankshaft having a longitudinal axis that is connected rotationally fixedly to the rotor; a piston-cylinder-unit that can be driven by the crankshaft, wherein, at an end of the crankshaft opposite from the piston-cylinder-unit, a sleeve-shaped lubricant receptacle is arranged for centrifugal conveyance of lubricant from a lubricant sump formed in a bottom region of the compressor housing in the direction of the piston-cylinder unit, wherein the sleeve-shaped lubricant receptacle has a fastening portion by which the sleeve-shaped lubricant receptacle is fastened to the crankshaft, wherein at least a section of the fastening portion of the sleeve-shaped lubricant receptacle is arranged, viewed in the radial direction relative to the longitudinal axis of the crankshaft, between the crankshaft and the rotor.
 2. The refrigerant compressor according to claim 1, wherein an inner surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts a circumferential surface of the crankshaft and in that an outer surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts an inner surface of the rotor.
 3. The refrigerant compressor according to claim 1, wherein the fastening portion of the sleeve-shaped lubricant receptacle is rotationally fixed between the rotor and the crankshaft.
 4. The refrigerant compressor according to claim 1, wherein an overlap of the rotor and the fastening portion in the axial direction relative to the longitudinal axis is more than 50% of the axial extent of the fastening portion relative to the longitudinal axis.
 5. The refrigerant compressor according to claim 1, wherein the sleeve-shaped lubricant receptacle has a rotationally symmetrical shape relative to the longitudinal axis, the diameter of the fastening portion being greater than or at least equal to the diameter of a receiving portion of the lubricant receptacle.
 6. The refrigerant compressor according to claim 5, wherein the fastening portion of the sleeve-shaped lubricant receptacle extends parallel to the longitudinal axis and in that the sleeve-shaped lubricant receptacle comprises a collar portion adjoining the fastening portion and extending radially outward relative to the longitudinal axis.
 7. The refrigerant compressor according to claim 1, wherein the fastening portion of the sleeve-shaped lubricant receptacle has at least one slot-like cutback, the rotor comprising at least one ridge corresponding to the cutback.
 8. The refrigerant compressor according to claim 1, wherein the electric drive unit is configured as an external-rotor motor and the rotor has at least one carrier element extending outward radially to the longitudinal axis, the carrier element being rotationally fixedly connected to the crankshaft.
 9. The refrigerant compressor according to claim 8, wherein the carrier element has a central through-opening for connecting the crankshaft, wherein an outer surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts a wall surface of the through-opening.
 10. The refrigerant compressor according to claim 9, wherein the through-opening is formed by a sleeve-like prolongation of the carrier element and in that an annular support element is pressed onto or shrink-fitted onto the sleeve-shaped prolongation.
 11. The refrigerant compressor according to claim 1, wherein the electric drive unit is configured as an internal-rotor motor, and the rotor has a central through-opening for connection to the crankshaft, wherein an outer surface of the fastening portion of the sleeve-shaped lubricant receptacle contacts a wall surface of the through-opening.
 12. The refrigerant compressor according to claim 1, wherein a lubricant driver is arranged in the interior of the sleeve-shaped lubricant receptacle.
 13. The refrigerant compressor according to claim 1, wherein the housing is hermetically sealable.
 14. The refrigerant compressor according to claim 1, wherein the lubricant receptacle is rotationally fixedly fastened to the crankshaft.
 15. The refrigerant compressor according to claim 1, wherein an overlap of the rotor and the fastening portion in the axial direction relative to the longitudinal axis is between 75% and 100% of the axial extent of the fastening portion relative to the longitudinal axis.
 16. The refrigerant compressor according to claim 6, wherein the collar portion of the sleeve-shaped lubricant receptacle bears against the rotor.
 17. The refrigerant compressor according to claim 7, wherein the at least one slot-like cutback extends parallel to the longitudinal axis over the entire extent of the fastening portion.
 18. The refrigerant compressor according to claim 12, wherein the lubricant driver and the lubricant receptacle are formed integrally. 